1. Field of the Invention
This invention relates to the thermal radiation measuring art, and, more particularly, to an improved arrangement for measuring thermal radiation from surfaces, as well as measuring the rate of heat flow between surfaces. Sequential thermal radiation detection steps can be followed to provide a measurement of the insulating value of, for example, walls, or other structures.
2. Background of the Invention
In the measurement of heat loss from buildings, as well as other structures, as well as detecting insulation defects and measuring insulation values, it has generally been desired to perform such detections and/or measurements as rapidly as possible. Further, it has often been desired to provide such detection and/or measurement without direct contact with the structure,
In buildings, for example, it is often desirable to know the heat loss from a building in order that appropriate insulation may be provided in the exterior walls thereof, as well as determining, for an existing building, the actual insulating value of the walls or other structures. There has heretofore been utilized several different techniques. In one technique, temperature measurements are made by direct contact with, for example, points on the inner surface and outer surface of an exterior wall. From the measured temperature difference the heat flow through the wall may be calculated. Such direct contact techniques have disadvantages in that the setup time for making the direct contact is comparatively lengthy at each location, and a comparatively large number of points of temperature measurement must be made in order to determine the overall heat flow through a wall.
In another technique which has heretofore been utilized, the inside surface and outside surface temperatures of a wall were measured indirectly by measuring the radiant output therefrom. From these measurements of the temperature by the radiation emitted from the wall surfaces, various nomographs and other charts were utilized to estimate both the heat flow through the wall, which is the heat energy lost, as well as the insulating value of the wall. Such techniques have required that various characteristics such as emissivity and the like be either ignored or approximated in making the appropriate measurements. This has often led to the introduction of errors in the measurements and other determinations based thereon. Further, even though the measurement of the temperature may be made more rapidly by detecting the radiation, this technique still suffers from most of the same disadvantages as the direct temperature measuring technique.
Since the ultimate desired result is a measurement of the actual heat flow through, for example, the exterior wall of a building, as well as obtaining the measurement of the insulating qualities of such a wall, it has long been desired to provide an accurate measurement directly of the heat flow rates involved.